1. Field of the Invention
The present invention relates to a rolling bearing provided with a shield plate, and a bearing device and an information recording and reproducing device which include the rolling bearing.
2. Background Art
Conventionally, there has been known an information recording and reproducing device such as a hard disc which magnetically or optically records various kinds of information therein and reproduces various kinds of information therefrom. In general, this type of information recording and reproducing device includes an actuator provided with a swing arm where a head portion which records a signal in a disc and reproduces a signal from the disc is mounted on a distal end of the swing arm. The actuator is rotatably supported on a bearing device mounted on a proximal end of the swing arm. That is, it is possible to rotate the swing arm along a horizontal plane by rotating the bearing device so that the head portion mounted on the distal end of the swing arm can be moved to a predetermined position of the disc whereby recording and reproduction of a signal can be realized.
The bearing device which rotates the swing arm is constituted of a shaft, a sleeve and a rolling bearing interposed between the shaft and the sleeve in general. Particularly, a rolling bearing which is used as this type of bearing device is required to be operated in a stable manner for a long period and hence, conventionally, it is often the case that a roller bearing provided with a shied plate is used.
This rolling bearing provided with a shield plate is a rolling bearing in which an annular shield plate (hermetically sealing plate) is mounted on an inner peripheral surface of an outer ring, and a circular annular space defined between a shaft and a sleeve is closed by a shield plate.
Accordingly, it is considered that the shield plate can prevent the adhesion of dusts or the like from the outside to rolling bodies, trajectory surfaces of the outer ring and the inner ring and the like, and can suppress leakage of grease, lubrication oil and the like in the inside of the roller bearing to the outside. Accordingly, the rolling bearing provided with a shield plate can be operated easily in a stable manner for a long period compared with a rolling bearing which is not provided with a shield plate.
As such a rolling bearing provided with a shield plate, for example, there has been known a rolling bearing which uses a shield plate provided with a plurality of engaging projections on an outer peripheral portion thereof (see JP-A-2002-89574).
In the shield plate adopted by the rolling bearing, a metal plate is formed into an annular shape, and the plurality of engaging projections are formed in a projecting manner on the outer peripheral portion of the metal plate along the circumferential direction at predetermined intervals. The plurality of these engaging projections are formed in a projecting manner such that the engaging projections are inclined obliquely toward the outside in the radial direction from the outer peripheral portion, and are deformable by bending in the orthogonal direction approximately orthogonal to the in-plane direction of the shield plate.
The shield plate having such a constitution is mounted on the outer ring by engaging the engaging projections with the inside of an engaging recessed groove formed on the outer ring.
To be more specific, the shield plate is pushed into the inside of a circular annular space defined between the outer ring and the inner ring such that the engaging projections are fitted into the inside of the engaging recessed groove. Due to such pushing, the engaging projections are fitted into the inside of the engaging recessed groove while being bent in the above-mentioned orthogonal direction using a proximal side as a start point. Then, when the shield plate is completely pushed into the inside of the circular annular space, the engaging projections elastically return in the inside of the engaging recessed groove due to an elastic restoring force so that the engaging projections push an inner surface of the engaging recessed groove. Accordingly, the engaging projections are caught by and are brought into an engagement state with the engaging recessed groove. In this manner, the shield plate is mounted on the outer ring.